Re: [Fetchmail-users] Weird Return-Path processing

[Skle.pik <sp...@ma...>]

On 27/03/2020 11:26, Matthias Andree wrote:
> Am 27.03.20 um 09:08 schrieb Skle.pik:
>> I did check POP3 side with Python poplib and clearly the Return-Path
>> is split across lines - result below:
>>
>> (b'+OK',
>> [b'Return-Path:
>> <noreply=abba.com__al4bl7qh36xreia2@35p9h14cih4s.6f-1gv0suag.ap',
>> b' 11.bnc.salesforce.com>',
>> b'Delivered-To:
>>
>> Does anyone know who is to blame - is this Return-Path formatting
>> violation on POP side, or maybe it is mailer being intolerant ?
> Looking at your Python trace and assuming it's represented properly
> here, the header isn't legit (per RFC5322) because the CFWS after the
> .ap at the end of the first line terminates the first atom or 1*atext
> and before the next atom/atext there would have to be a dot, so you'd
> need to trace back to the originator (which may or may not have been
> Salesforce) where it broke, or if the originator who pretended to have
> been (and may or may not have been) Salesforce sent garbage already.
Thanks for confirming my suspicion. This is enough to work with email 
provided as I suspect upstream POP server to be guilty here.
> However you seem to be proving that fetchmail is not unfolding the line
> properly, and is shipping out this broken line via SMTP (RFC5321), which
> isn't permitted either, the SMTP Domain can't have blanks or line
> breaks, so this seems to be a bug. Given that RFC5322 Return-Path:
> header syntax is more permissive than RFC5321 SMTP MAIL FROM:<...>
> syntax, fetchmail needs to validate input and act accordingly.
Ok, so what would be fetchmail action then ? Skipping pushing message 
based on malformed field detection ?
>
> FTR, which fetchmail version are you using?c
It is 6.3.26 but I checked several 6.3.x versions and they all handle 
this case in similar way (except maybe from really old 6.3.8 which did 
removed the message from the server despite SMTP failing).
>
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